Autologous Bone Peg Grafting for Distal Phalanx Nonunion: A Report of Two Cases

Abstract

Distal phalangeal nonunion is a rare but challenging condition that may result from crush injuries or inadequate stabilization. Surgical fixation is often difficult because of the small size of the fragment and surrounding soft tissue damage. We report two cases of symptomatic distal phalanx nonunion successfully treated with autologous bone peg grafting. The first case involved a 13-year-old boy who developed nonunion following a bicycle injury. The second case involved a 31-year-old man who sustained an open fracture in a workplace accident. In both cases, a cortical bone peg harvested from the posterior aspect of the ipsilateral proximal ulna was inserted into the medullary canal of the distal phalanx to provide mechanical stability and promote bone healing. Radiographic union was achieved within 3 months, and both patients returned to full activity, with one experiencing minor residual symptoms.

Nonunion of the distal phalanx is relatively rare but may occur particularly after open or tuft fractures, crush trauma, or insufficient stabilization.¹ Recent nationwide and institutional studies have identified risk factors such as older age, tobacco and alcohol use, and obesity.² Although many nonunions remain asymptomatic, painful cases can compromise fine motor tasks and daily function. Surgical treatment options include Kirschner wire fixation, mini screws, and bone grafting, but these can be technically challenging, especially when the fragment is small or the nail bed is involved.^3,4

Bone peg grafting offers the dual advantage of mechanical fixation and biological stimulation for bone healing.^5,6 However, reports on its use in distal phalangeal nonunion are limited.

In this report, we present two cases of distal phalanx nonunion successfully treated with autologous bone peg grafting harvested from the proximal ulna. Both patients achieved bony union without major complications, demonstrating the utility of this technique for these challenging cases.

Case Reports

Case 1

A 13-year-old boy sustained a distal phalangeal fracture of the right middle finger after falling from a bicycle. He was initially treated conservatively with closed reduction and splinting at a local clinic. However, follow-up radiographs showed progressive displacement and nonunion (Fig. 1A).

Figure 1.

Case 1: A 13-year-old boy with distal phalanx nonunion and displacement in the right middle finger. A Radiographs at referral showing distal phalanx nonunion. B Postoperative radiographs after initial pinning, showing nonunion at 11 months. C Intraoperative views during bone peg grafting. The dotted white lines indicate the outline of the inserted bone peg before trimming. D Radiographs at 3 months after surgery showing bone union.

Approximately 9 weeks after injury, he was referred to our hospital with persistent pain at the fingertip. Radiographs and computed tomography imaging demonstrated a clearly separated distal fragment with sclerotic changes, consistent with a diagnosis of nonunion.

Initial surgical treatment included open reduction and internal fixation using a 1.0 mm (0.039 in) Kirschner wire via a volar approach. However, bone union was not achieved at 11 months after surgery, and persistent instability was noted (Fig. 1B).

As a secondary procedure, we performed bone peg grafting under general anesthesia. A 1.5 mm Kirschner wire was used to create a canal across the nonunion site. A cortical bone peg was harvested from the posterior aspect of the ipsilateral proximal ulna. A longitudinal skin incision approximately 2.5 cm in length was made approximately 4 cm distal to the olecranon tip. The periosteum over the ulnar crest was elevated to expose the cortical surface. A rectangular segment of cortical bone measuring approximately 2 mm in width and 18 mm in length was outlined. First, four corner holes were drilled with a Kirschner wire to define the graft’s borders. Next, vertical cuts were made with a bone saw, followed by transverse cuts along the short sides using an osteotome. Finally, the bone peg was lifted and extracted by inserting a 1.8 mm Kirschner wire or osteotome into the vertical cuts and levering the segment out (Fig. 2A–D).

Figure 2.

The graft is obtained through a 2.5 cm longitudinal incision located approximately 4 cm distal to the olecranon tip on the posterior aspect of the proximal ulna. Schematic illustration of the bone peg harvesting technique. A Four corner holes are made with a Kirschner wire. B Vertical cuts are performed using a bone saw. C Transverse cuts are made with an osteotome. D A 1.8 mm Kirschner wire or osteotome is inserted into the vertical cuts to lift the peg.

The harvested peg was then inserted through the fingertip into the medullary canal to span the fracture site. The tip was trimmed to avoid soft tissue irritation. After surgery, the distal interphalangeal (DIP) joint was immobilized in extension using an aluminum splint for 6 weeks (Fig. 1C).

At 11 weeks after surgery, radiographic union was confirmed. The patient reported no functional limitations and was asymptomatic (Fig. 1D).

Case 2

A 31-year-old man sustained an open crush injury to the left middle fingertip while operating machinery at work. He initially received local irrigation, splint immobilization, and a tetanus toxoid injection at a nearby clinic. Two days later, he was referred to our hospital (Fig. 3A).

Figure 3.

Case 2: A 31-year-old man with a comminuted fracture of the left middle finger distal phalanx that progressed to nonunion. A Radiographs at injury showing comminuted fracture. B Radiographs at 3 months after pinning and removal, showing nonunion. C Intraoperative views during bone peg grafting. The dotted white lines indicate the outline of the inserted bone peg before trimming. D Radiographs at 3.5 months after surgery showing bone union.

Under digital block anesthesia, we performed percutaneous pinning with a 1.0 mm Kirschner wire and repaired the nail bed. Despite initial stabilization, bone loss at the fracture site and persistent instability led to nonunion (Fig. 3B).

As a secondary procedure, we performed autologous bone peg grafting under supraclavicular brachial plexus block anesthesia. A canal was drilled through the fingertip across the nonunion site using a 2.0 mm Kirschner wire. As in Case 1, a cortical bone peg was harvested from the posterior aspect of the ipsilateral proximal ulna using the same technique and inserted into the medullary canal to bridge the nonunion site (Fig. 3C).

The graft tip protruding beyond the fingertip was trimmed, and the wound was closed. After surgery, the DIP joint was immobilized in extension using an aluminum splint for 6 weeks.

Postoperative radiographs confirmed stable alignment and good graft placement. Radiographic union was achieved within 3 months. The patient experienced mild cold-induced discomfort but was able to use the affected finger in daily life and work without any functional limitations (Fig. 3D).

Written informed consent for publication, including the use of clinical images, was obtained from both patients. There is no information in this manuscript that can identify the patients (names, initials, hospital identification numbers, or directly identifying photographs).

Discussion

In this report, we describe the successful use of autologous cortical bone peg grafting harvested from the posterior aspect of the proximal ulnar shaft to treat distal phalanx nonunion in two distinct cases. Both patients achieved radiographic union within 3 months and returned to their previous levels of activity without major complications, supporting the feasibility of this technique when metallic fixation is unsuitable. Although painful nonunion can compromise fine motor tasks such as pinching, writing, or buttoning and thereby affect daily function, surgical intervention may also be justified even when subjective pain at rest is minimal. Particularly in young or high-demand patients, surgical reconstruction of a distal phalanx nonunion should be considered to restore structural integrity and prevent secondary complications such as progressive nail deformity or DIP joint arthrosis. Traditional surgical methods such as Kirschner wire fixation or screw osteosynthesis can be limited by small fragment size, poor soft tissue conditions, and hardware-related issues, particularly in manual laborers.³

Bone peg grafting provides both mechanical stabilization and biological stimulus for bone healing. Kim et al⁶ reported favorable results using autogenous bone pegs in cases of distal phalanx nonunion, achieving union without hardware-related complications. Similarly, Shinomiya et al⁵ demonstrated that autologous bone pegs offer sufficient fixation without the need for metallic implants, reducing the risk of irritation and eliminating the need for subsequent implant removal.

Although Kim et al⁶ harvested bone pegs from the ilium, radius, and olecranon of the ulna, we obtained cortical grafts from the posterior aspect of the proximal ulnar shaft, distal to the olecranon tip. This approach enables graft harvesting through a smaller surgical field on the same limb, eliminating the need for repositioning or preparation of a separate donor site.

Moreover, this method allows for harvesting a straight and rigid cortical bone segment well-suited for use as a bony peg, with minimal need for postharvest shaping or trimming. Additionally, it may reduce operative time and donor site morbidity.

In the two cases presented, bone peg grafts harvested from the ipsilateral ulna were successfully used to stabilize the nonunion site. The procedure allowed for direct insertion through a minimal incision and did not require additional fixation. Both patients achieved radiographic and clinical bone union within 3 months and returned to their previous levels of activity. The first patient became asymptomatic, whereas the second noted only minor residual symptoms.

This technique is particularly useful in situations where the distal fragment is too small for screw fixation or where metal implants may interfere with the nail bed or soft tissue. Furthermore, surgical incisions in the distal phalanx carry inherent risks of complications, including neuromas and iatrogenic nail deformities. To minimize these risks, we used a midline volar approach or direct fingertip entry, carefully avoiding the nail matrix and major digital nerves. Consequently, no neuromas or new nail deformities were observed in our patients. Additionally, it eliminates concerns related to hardware removal or soft tissue irritation.

Despite requiring technical familiarity and caution in narrow or sclerotic canals, the procedure is reproducible when performed as described. Bone peg harvesting from the proximal ulna is straightforward and was safely achieved through a small incision, with no donor site complications observed.

In conclusion, autologous bone peg grafting is a simple and effective surgical option for distal phalangeal nonunion, especially when metallic fixation is not feasible.

Ethics declaration

Written informed consent to take part in the study and to publish the article has been obtained from all participants or their legal representatives. The privacy rights of participants have been observed.

This study was performed in compliance with relevant laws, regulatory frameworks and guidelines where the research took place. Ethics committee approval was not required under relevant laws and institutional guidelines. According to the local institutional guidelines and the Ethical Guidelines for Medical and Biological Research Involving Human Subjects in Japan, ethics committee approval was not required for this retrospective report of two clinical cases treated within the standard routine care.

This research follows the CARE guidelines and the CARE checklist.

Declaration of Generative AI and AI-Assisted Technologies in the Writing Process

During the preparation of this work the authors used ChatGPT (OpenAI) and Gemini (Google) for language editing and formatting suggestions. After using these tools, the authors reviewed and edited the content as needed and takes full responsibility for the content of the publication.

Conflicts of Interest

No benefits in any form have been received or will be received related directly to this article.